How do I ; Clean pickups and alter my trush rod

I made a huge mistake. When I changed my strings I took all my old strings off and then I went and did some other stuff. I came back to my bass about four hours later and then when I put my new strings on they sounded really tinny.I think that leaving my strings off my bass has screwed up the neck, with there being no tension and stuff.I'm pretty ignorant when it comes to the trush rod, i've always taken my bass to a guitar shop when i've needed it altered before. However, I live in the middle of nowhere and I can't get to a decent guitar shop for another week or so and this is urgent. My bass is an Aria Pro 2 IGB-68 if that helps any.I need to know how to alter the trush rod so my guitar sounds less tinny and more like it is supposed to. I need any advice you can give.

Also, how do I clean my pickups ?I have humbucker pickups, I don't know their correct name, they are the same as those on the music man stingray bass. The exposed metal parts have turned from bright silver to a murky brown. How do I get them clean and sparkling again?